A problem that has me stumped...

[skinner]

I have a 98 with the 3.0L engine. It has developed a misfire and the coolant reservoir tends to bubble when the engine is shut off(it may bubble driving, I don't pay attention much then ). Naturally I would think a head gasket. However, there is no smoke out the exhaust, the oil looks brown, the antifreeze looks mostly green(some rust/brown color). It reads a lean code on one bank...will a head gasket do that? Compression shows fine except one cylinder about 15 psi lower(on that same bank, mind you). Spark plugs don't show any antifreeze marks i'm used to. Ran a block test from AZ today and the chemical did not change colors, indicated that theres not a lot of exhaust carbons in the radiator. So i'm stuck. I dont want to rip the entire engine apart if i don't have to, yet dont want to just do the intake manifold up if it really is the head gasket. What else can cause antifreeze use and for it to boil over(well, probably not boiling, looks more like air coming up)? Like I said, temperature is fine. It does misfire. It shows 7 CEL codes...EGR and O2 sensor related...only one of real interest is one bank running lean. I'm thinking of just doing the intake manifold gasket and water pump. But i don't want to piss money into the wind. Is there a more accurate test?

 

[86freebie]

i dont think misfire is related to the boiling when shut off

what is probably happening is when you shut off the truck the water around the pistons is starting to boil when you shut it off.

get some radiator flush, flush it, then refill with a good 50/50 mixture. and replace the radiator cap. if it is week it will let it boil, especially if the coolant is not strong enough to raise the boiling point. and for about 10 dollars you might as well change the thermostat. don't rely on the gauge and say it is, or its not running hot(unless it is a mechanical gauge.)

that should fix that.

 

[mlunsford]

Sounds like a blown head gasket or cracked head. Try a leak down test.

 

[MAKG]

Boiling with the engine OFF?

That doesn't indicate a blown head gasket. It means the cooling system has some air in it. That's all. Now, it MIGHT come from a blown head gasket, but there is no reason to think it does.

That it's apparently fouled means it needs flushing.

As for the lean code, I'd fix all the other codes first if I were you. Lean codes are a b*tch, as there are many causes. You may find one of the other codes fixes it.

Multiple codes often indicate problems with grounding, power, or VREF.

 

[Copytech]

I had a 3.0 Taurus that did the exact same thing as your truck.I couldn't figure it out till the water pump failed, put on a new one and it ran fine.

 

[skinner]

Thanks for the replies guys. I ran a chemical test at the radiator to find no exhaust gasses. But since it had 7 codes or so stored, I went ahead and decided to rip it apart down to the block. No, i'm not a complete moron, it's not yet my daily driver and want to make sure everythings good to go before I make it that. Aside from a slight bent exhaust seat, gasket and heads are fine. However, three of the intake bolts were just kinda sitting there, easily unthreaded by finger. I figure its either that or also the water pump at this point. I'm going to do the pump while I got it apart. I'll report back at the end of the week when I have my heads back(having valve job done and exhaust seat changed) and the engine reassembled.
And since I get 30% off parts this weekend, I went ahead and bought MAF sensor, both front O2 sensors, EGR valve, egr pressure sensor, all gaskets, water pump, tstat, and a few hoses.
Hopefully get er running top notch.

 

[MAKG]

Problems like you report are fairly often none of the above.

A rotted out battery cable, especially one with a broken pigtail, can do it, for instance.

 

[skinner]

Well, the codes were, to some extent
All oxygen sensors
2 EGR codes
A manufactureres a/f metering system code
and a bank 2 lean code.